System and method for controlling a power generating system

ABSTRACT

This invention overcomes the disadvantages of the prior art by providing a power generating system particularly suitable for field use in remote locations, which is fuel-efficient, relatively quiet, tolerant of dust, capable of operating on low grade logistics and diesel-like fuels and capable of generating between 500 W and 2 KW of continuous electrical power. This generating system employs a two-cycle MICE generator having a piston that operates within a cylinder, and an interconnected, axially moving piston shaft that oscillates an alternator coil within a magnetic core. The piston shaft is attached to, and resisted by, the free end of a strong spring with a second, opposing end fixed to the MICE casing. To control operation of the MICE generator a dual clipper circuit is operatively connected with the alternator coil. The clipper circuit senses the current and at least two voltage levels and applies at least two respective loads in response to the sensed voltage levels and current so as to (a) prevent overstroke of the piston and (b) control power output of the alternator coil. The MICE generator also includes a fuel intake preheater that selectively heats fuel/air mixture entering the casing and a controller that senses load on the alternator coil varies a level of preheating to thereby control a level of power output.

STATEMENT REGARDING FEDERALLY SUPPORTED RESEARCH OR DEVELOPMENT

This invention was made with government support under Small BusinessInnovation Research awards: H92222-05-P-0028 and DAAB-15-03-C-0011. Thegovernment has certain rights in this invention.

RELATED APPLICATIONS

This application is related to commonly owned copending U.S. patentapplication Ser. No. 11/326,704, entitled POWER GENERATING SYSTEM, filedon even date herewith, by Kurt D. Annen, et al., which is expresslyincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present application relates to small portable power sources and moreparticularly to small combustion motor generator power sources.

2. Background Information

For over a century there has been a need to generate electric power inthe field, away from a reliable source of continuous power, such as theutility grid. Remotely generated power has, and continues to be, neededto operate lighting, equipment, radios and other key devices. Standardapproaches to generating or supplying remote power have centered arounda few basic technologies, namely: (a) a precharged battery assembly thatis sized appropriately for the load and duration, (b) a motor generatorpackaged that operates a dynamo or alternator sized in output thatsatisfies the expected load; (c) a hybrid having a motor-generator,battery assembly combination, and (d) a “Stirling” cycle generator. Eachof these prior art approaches has limitations.

In the first type, the battery packs are heavy, have limited power, andshort duration (in normal use, after one hour or so the battery packneeds to be removed and recharged).

For the second type, traditional fuel-powered motor-generators (Dieselor Otto cycle-type) using rotary crank shafts and pistons are heavy,noisy, and not particularly portable, and therefore impractical in manyapplications that require frequent movement, often on foot through roughterrain. The typical motor generator used on a field construction sitemay be quite large and heavy to lift. It is usually dropped in one placeand connected to a device or plurality of devices by a cord, often tensof feet long. Its construction and weight do not lend themselves tofrequent movement and/or placement close to the device. These prior artmotor generators are large because, while the average power is not high(less than 50-200 watts), the peak power output may be many times largerwhile a device is actually operating.

The third type of generation approach is derived from automotivetechnology, where a small engine charges batteries in a “hybrid” vehiclecontaining the batteries and the internal combustion engine. However,such automotive-sized components (engine generator and batteries) aresignificantly larger than needed for most field applications (a fewwatts (W) to 1-2 kW) they do not scale down well. In particular, thesmaller the engine, the larger the battery needed to store power, so asto ensure sufficient peak power will remain available at all times.Moreover, where a connected device is run continuously, the engine muststill be sized to deliver energy that matches or exceeds the device'spower demand or the battery will slowly discharge as the system fallsshort of the continuous demand.

A fourth type of generation approach, known as the Stirling cycleengine, while having good combustion, is potentially quiet and istolerant to ingesting particles. However, conventional designs have ahigh weight to power out ratio.

An alternate approach for providing a two cycle crankless engine thatintegrates an alternator coil with a sprung inline piston is taught incommonly assigned and published U.S. Pat. No. 6,349,683 entitledMINIATURE GENERATOR by Kurt Annen, et al., the teachings of which areexpressly incorporated herein by reference. This engine employs a strongmulti-helix spring to buffer the power stroke of a piston that moves analternator coil through a permanent magnet to generate AC power. Thispower is conditioned to provide the needed DC voltage for operating apower tool or similar device. A small recharging battery or capacitorcan be interconnected to the alternator and device motor to provide peakoutput current when needed. The motor of this system is surprisinglysmall and light, being comparable in size to a small scale modelairplane engine. It is herein termed a miniature internal combustionengine (MICE)/generator.

Such performance significantly exceeds that available from aconventional crankcase engine/generator or a charged battery array for agiven weight/size. This technology lends itself to a larger scaleapplication, such as field power generation in, for example, the12-24-28 VAC or VDC range with power output of, for example, 500 W to1-2 KW.

SUMMARY OF THE INVENTION

This invention overcomes the disadvantages of the prior art by providinga power generating system particularly suitable for field use in remotelocations, which is fuel-efficient, relatively quiet, tolerant of dust,capable of operating on low grade logistics and diesel-like fuels andcapable of generating between 500 W and 2 KW of continuous electricalpower. This generating system employs a MICE generator having a pistonthat operates within a cylinder arranged for two-cycle operation, and aninterconnected, axially moving piston shaft that oscillates analternator coil within a magnetic core. The piston shaft is attached to,and resisted by, the free end of a strong spring with a second, opposingend fixed to the MICE casing. To control operation of the MICE generatora dual clipper circuit is operatively connected with the alternatorcoil. The clipper circuit senses the current and at least two voltagelevels and applies at least two respective loads in response to thesensed voltage levels and current so as to (a) prevent overstroke of thepiston and (b) control power output of the alternator coil.

In another embodiment the MICE generator includes a fuel intakepreheating assembly that selectively heats fuel/air mixture entering thecasing and a controller that senses load on the alternator coil and thatvaries a level of heating by the preheating assembly to thereby controla level of power output by the piston and alternator coil. In thismanner, increase in the preheat level can result in reduced power outputby the MICE generator and decrease in the preheat (which increasesresulting fuel/air mass flow) can increase power. In an illustrativeembodiment, the fuel intake preheating system includes a heated-fluidtransfer assembly that transfers heat from another location of thecasing to a fuel intake assembly.

This invention also contemplates a system and method for startup of aMICE-based generating system according to this embodiment that includesoscillating the MICE piston by providing power to the alternator coilfrom an electrical storage assembly and sensing a power output at apredetermined level from the coil and, in response to the sensing of thepredetermined level, suppressing or disconnecting the power from theelectrical storage assembly. The fuel is atomized by a MEMS, orequivalent atomizing assembly (ultrasonic, for example), prior tointroduction into the MICE generator. In this manner, the MICE generatorcan operate using low-volatility (diesel-like) fuels.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention description below refers to the accompanying drawings, ofwhich:

FIGS. 1A-1D are side cross sections of a cylinder head/piston of a basictwo-cycle internal combustion engine;

FIG. 2 is a side cross section of a miniature internal combustion engine(MICE) generator used in connection with the power generating systemaccording to an illustrative embodiment of this invention;

FIG. 3 is a side view of a double-helix spring for use with the MICEgenerator according to the embodiment of FIG. 2 detailing rounded stressreliefs formed at the joints between the helix ends and the respectivetop and bottom spring ends;

FIG. 3A is a bottom end view of the spring of FIG. 3 detailing internalstress reliefs on the free end base;

FIG. 4 is an external perspective view of the MICE generator of FIG. 2;

FIG. 5 is a partial exposed side view of a cooling head mounted over thecylinder head casing of the MICE generator of FIG. 2;

FIG. 6 is a flow diagram describing a procedure for regulating coolingbased upon sensed temperature at the head of the MICE generator;

FIG. 7 is a flow diagram describing a procedure for regulating coolingbased upon sensed power output from the MICE generator;

FIG. 8 is a partial side cross section of the MICE generator in the areaof the intake plenum detailing a plenum heater according to anillustrative embodiment;

FIG. 9 is a flow diagram describing a procedure for controlling outputbased upon plenum heating;

FIG. 10 is a partially exposed side view of a combined MICE cylindercasing cooling head and plenum heating arrangement with auxiliary heatand heat exchanger according to an illustrative embodiment;

FIG. 11 is a partially exposed perspective view of a sound-dampening,acoustic enclosure for the MICE generator according to an illustrativeembodiment;

FIG. 12 is a fragmentary side view of the vibration isolation assemblyincluding the acoustic enclosure base plate and MICE generator mountingassembly according to an illustrative embodiment;

FIG. 13 is a fragmentary side view of the vibration isolation assemblyincluding the enclosure base plate and MICE generator mounting assemblyfurther detailing the fixed attachment of intake and electrical leads tothe MICE generator and base plate according to an illustrativeembodiment;

FIG. 14 is a side cross section of an exemplary packaging arrangementfor generating system components according to an illustrativeembodiment;

FIG. 15 is a side cross section of an exemplary packaging arrangementfor generating system components according to an alternate embodiment;

FIG. 16 is a flow diagram detailing an exemplary start-up procedure forthe MICE generator according to an illustrative embodiment;

FIG. 17 is a schematic circuit diagram of a dual clipper circuitoperatively connected with the MICE generator electrical output forregulating overstroking and load in accordance with an illustrativeembodiment;

FIG. 18 is a somewhat schematic diagram of a heated-fluid exhaust jacketinlet heating arrangement according to an illustrative embodiment;

FIG. 18A is a somewhat schematic diagram of an heated-intake-air exhaustjacket inlet heating arrangement according to an alternate embodiment;

FIG. 19 is a side view of a spring assembly having two stacked,concentric springs according to an alternate embodiment; and

FIG. 20 is a schematic diagram of a plurality of exemplary applicationsfor the generating systems according to the various embodimentscontemplated herein.

DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT

A. Operating Cycle of a MICE Generator

To further illustrate the operative principles of the MICE generator ofthis invention, reference is first made to FIGS. 1A-1D, which illustratethe operation of a typical two-cycle engine, such as those found in asmall-scale model airplane.

FIG. 1A shows the cylinder head 102 of a two-cycle engine with aringless piston 104 that drives a piston rod 105, shown at the top ofits stroke. A glow plug 106 provides the ignition source during startup,and optionally during steady operation, to existing fuel/air mixturethat is compressed in the space of the upper chamber 126 between thepiston 104 and the top 107 of the cylinder head 102. As the piston 104moves toward the top of the stroke, fuel-vapor/air mixture (representedby arrow 108) is contemporaneously drawn into the lower chamber 110 viaan inlet port 112.

FIG. 1B shows the piston 104 after completion of the power portion ofthe expansion stroke that delivers power to the piston rod 105. Thecombustion products 114 (arrow 114) are ejected via an exhaust port 116,and the piston closes off the inlet port 112 and forces the fuel/airmixture 120 in the lower chamber 110 into a transfer port 122, formed asa slot in the cylinder sidewall. The transfer port selectively bridgesthe upper chamber 126 and lower chamber 110 as the piston reciprocatesin the cylinder.

As shown in FIG. 1C, the piston 104 has moved approximately to thebottom of its stroke. As such, fuel/air mixture in the transfer port 122enters (arrow 124) the upper cylinder chamber 126.

Now, referencing FIG. 1D, the piston is just beyond the point in thecompression stroke at which both the exhaust port 116 and transfer port122 are effectively closed off. The inlet port 112 is also closed atthis point so that a vacuum develops in the lower chamber 110 to effectthe drawing in of the fuel and air mixture when the inlet port 112 openslater in the compression stroke. At this point in the cycle, thefuel/air mixture is being compressed in the upper cylinder chamber 126,in preparation for ignition by the glow plug 106. At such time theexhaust port 116 and transfer port 122 are again closed off from theupper chamber as shown in FIG. 1A while the inlet port 112 is open toadmit a new charge of fuel/air mixture.

B. General Construction of the MICE Generator

Having described the basic operation of a two-cycle engine similar tothe inventive MICE generator described herein, reference is now made toFIG. 2, which shows an illustrative embodiment of the MICE generator 200for use in the electric power generation of this invention.

The upper portion 202 of the MICE generator 200 shows the cylinder headcasing 203 having a geometry described in general terms for FIGS. 1A-1D.The piston 204 (constructed from 440 stainless steel alloy in thisexample) rides vertically/axially (as depicted) within the cylinder headcasing 203, sliding within the walls of a sleeve that defines theinternal cylinder 206. Notably, the piston is ringless and insteadrelies upon a relatively tight fit with respect to the cylinder wall tomaintain compression. The cylinder 206 is constructed from steel alloy(for example, 12L14 alloy as it contains lubricating lead) in anillustrative embodiment. In an alternate embodiment, ductile cast ironcan be employed, among other materials. An exhaust port 210 is definedby a cut-slot on the left side (as depicted) of the casing 203 andcylinder 206. The inlet port 212 is located on the opposing right side,vertically below the exhaust port. The inlet and exhaust ports arelocated opposite each other on the head to assist in balancing pressureand flow though the head during operation, which assists in preventingunwanted seizure of the piston. The inlet port 212 includes a lower wall214 angled at approximately 30 degrees, tapering outwardly toward theexterior of the casing 203. The taper (214) assists in porting fuel/airmixture (described further below) into the lower cylinder chamber 216via a plenum space 218, enclosed by an inlet plenum casing 220 alsodescribed below. The taper also increases the separation between theinlet and exhaust ports at the outer cylinder casing for simple inletplenum design. The top of the inlet port 212 is located to besubstantially in line with the bottom of the piston 204 when it is atthe top of its stroke in this embodiment. This serves to reduce the MICEgenerator's “scavenging” loss (e.g. the amount of uncombusted fuel/airmixture lost prior to ignition through the exhaust port) as the pistoncloses the inlet port 212 earlier in the cycle and thereby reducesbackflow. In the illustrative embodiment the piston head 204 has adiameter DP of approximately 25 mm and an axial length LP ofapproximately 27 mm. The integral piston rod had a length ofapproximately 150 mm. The piston 204 can also be coated with ahard-friction reducing substance such as MicroBlue (available fromMaterial Technologies, Inc. of Rockford, Ill.), electroless nickel orTiN according to various embodiments.

As will be described in detail, the overall construction of the MICEgenerator enables the use of low-volatility logistics fuels, such asdiesel fuel or JP-8 (Jet-A fuel without-additives) and various mixturesthat include such compounds, among others. The exhaust port 210 islocated above the plenum so that exhaust gas does not mix with intakefuel/air mixture. The exhaust port and/or the inlet port can includevertical ribs (not shown for clarity) that divide the port in thecylinder wall, and optionally, the casing wall, to provide a continuoussurface between the piston and cylinder and reduce maximum interfaceloads.

The casing and cylinder walls include a transfer port structure 222. Inone embodiment, an opposing, identical structure (not shown) is providedcircumferentially opposite the depicted transfer port. A lower port 224of the overall structure 222 is formed through the cylinder 206, and isopen to the lower chamber 216 until the piston 204 reaches the bottom ofits stroke. A channel 226 (shown in phantom) behind the cylinder 206routes mixture to a top port 228, which is open when the piston nearsthe bottom of the stroke, thereby allowing fuel/air mixture to pass intothe upper (combustion) chamber 230 for subsequent ignition at the top ofthe stroke. A catalytic glow plug 232, fitted into a threaded glow plugreceptacle 234 at the top 236 of the cylinder casing 203 is provided toeffect ignition on startup and optionally during steady operation.

The lower end of the cylinder 206 engages a flange 238 that encirclesand extends radially from the cylindrical wall 240 of a bearing sleeve242. The bearing sleeve 242 defines an open space 244 in communicationwith the bottom chamber 216 of the cylinder 206. This space 244 issealed at the bottom by a base wall 246 of the sleeve 242. The lowerside of the base wall 246 includes a recess that carries a piston rodbearing insert 248. The sleeve is of aluminum preferably with an insert(not shown) made from Vespel® polyimide (trademark owned by DuPont) orother like bearing material known in the art. In an embodiment, theinsert 248 is secured into the recess by a cover plate 250 that can befastened to the base wall 246 using rivets, screws or similar fasteners(252), disposed around the circumference of the plate at variouslocations.

The insert 248 defines a gas seal against the piston rod 260. This rod260 extends vertically along a central axis 262 of the MICE generator.The rod 260 thereby transmits the axially directed, linear force of thepiston 204, derived from a combustion-generated expansion stroke, to thespring assembly and alternator assembly (described below). The rod 260also transmits the axially-directed, linear force of the spring to thepiston head on the compression stroke. In an illustrative embodiment,the piston rod 260 is constructed from hard steel and is rigidlyattached to the piston. The rod 260 is either a unitary member, formedsimultaneously with the piston 204, or a separate component that iswelded, threaded or press-fit into the piston 204. Alignment of the rod260 along the axis 262 is significant. In an embodiment in which the rod260 is rigidly attached to the piston and, itself, rigid, anymisalignment will cause the piston to skew in the cylinder, therebygenerating friction and excessive wear between the piston and cylinderwall. Likewise, because the clearance between the coil and the magnet ofthe alternator assembly (described below) is very small, unwantedtransverse movement will produce contact causing friction and possibledamage to these components.

In an alternate embodiment, minor misalignment of the rod with respectto the axis 262 can be tolerated where the rod is somewhat flexible, orconnected to the piston using a flexible and/or joint that displacesradially (e.g. on a plane perpendicular to the axis 262).

The space 244 defined by the bearing sleeve 242 is adapted to provideimproved scavenging of fuel/air mixture during operation by appendingvolume to the lower chamber 216 and effectively defining a “scavengingchamber” in which additional volume for retaining fuel/air mixturewithout loss through the exhaust is provided. The additional volume alsoreduces the parasitic scavenging compression work, and can be sized toimprove the pressure tuning of the inlet processes. The scavenging ratioachieved in an operative version of the MICE generator is in the rangeof approximately 75-80% using JP-8 or similar fuel.

It is noted that the scavenging ratio achievable by the MICE generatoris limited by the backflow that occurs through the inlet and transferports prior to their closing. This backflow could be reduced oreliminated by use of reed or flapper valves (not shown) that close theport when the flow is reversed. Reed valves could be used moreeffectively on the inlet port given their size and shape. Alternatively,a fluid diode can be employed within the transfer port to reducebackflow. The use of such valves/diodes should be balances against anyinherent pressure loss that they introduce to the system.

The cylinder casing 203 engages a threaded insert 264 within its lowerend 266. The lower end 266 includes a radially extended flange 268 thatprovides a base for the plenum casing 220, and also to provide aconfronting attachment surface for the top of the spring casing 270 asdescribed below. The inner surface of the extended flange 268 isprecisely machined to have a close fit to the spring outer flange 285 toensure close alignment of the central axes of the cylinder 206, thebearing sleeve 242 and insert 248, and the multiple helix spring 286.The top of the threaded insert 264 bears against a thin, rigid springmaterial 272. This spring 272 engages the bottom of the bearing sleeveflange 238, the top of which flange engages the cylinder 206. The spring272 exerts an upward axial force on the cylinder, driving it (relativeto the casing 203) against a copper gasket (approximately 10 mils thick)274 located between the casing top 236 and the cylinder top 236. In thismanner, the spring ensures 272 that the cylinder 206 remains positivelysealed against both the bearing sleeve 242 and the top of the cylindercasing, thereby preventing loss of compression.

The cylinder head casing flange 268 is fixed securely to the underlyingspring housing at a confronting spring housing flange 276 employing amulti-section split ring clamp assembly 278, 280 and 282. A variety ofstructures can be employed in alternate embodiments. Notably, the clampassembly includes an upper clamp ring 278 that also engages a base ring284 of the plenum casing 220; a lower clamp ring 280, that engages theexterior of the spring housing flange 276; and an external split ring282 that rides on ramps formed in each ring 278, 280 to translateinwardly directed radial force into axial compression within the rings278, 280. The inwardly directed radial force can be provided to thesplit ring by an overriding hose clamp or similar hoop-stress-generatingmechanism (not shown). This clamping arrangement provides a highlysecure, removable and rigid interconnection between the cylinder casing203 and the spring housing that is free of play in either the axial orradial direction.

In this embodiment, the clamping arrangement also engages the radiallyextended shoulder of the top fixed end 285 of a multi-helix compressionspring 286. The spring 286 compresses axially. In this embodiment, atleast two opposing helices (see also FIG. 3) are formed in the springstructure so as to balance the torque produced in each helix, therebyavoiding transverse movement of the bottom of the spring causingmisalignment and piston/cylinder scoring or seizing. In this embodiment,the opposing helices are formed by machining the structure from aunitary piece of titanium alloy rod. Titanium-6A1-4V alloy havingexcellent fatigue strength is employed in this example. The size andshape of the spring are set based upon a safety factor of 1.4 or greaterbased upon the maximum force produced at the extremes of the springmovement as determined by the MICE generator design stroke. Each helixincludes three-and one-half turns in this embodiment. The spring is atrest with the piston located approximately one-half stroke above thebottom of the exhaust port, as shown.

With reference also to FIG. 3, a side view of the machined double helixspring 286 according to an illustrative embodiment is shown. In thisillustrative embodiment, the diameter DS of the compressible portion ofthe spring 286 is about 5.4 centimeters and the top end shoulder 285 hasa larger diameter DSS about 6.4 centimeters. The total length LS of thespring 286 including the shoulder 280 at the unitary top end and theunitary bottom end 284 is about 11.7 centimeters. The pitch of eachhelices 310, 320, in a preferred embodiment, is about 2.54 centimeters.Each helix 310, 320 includes a rectangular (rather than circular) crosssection (refer to FIG. 2). This cross section, in an illustrativeembodiment includes a vertical dimension HCS of approximately 0.75centimeters and a radial/horizontal dimension RCS of approximately 0.75centimeters. The unitary bottom end piece 287 is arranged with aprecisely bored hole 330 (shown in phantom) that matches aclosely-fitting portion of the piston rod (288) below a shoulder in thepiston rod (260). A threaded end to the piston rod below theclosely-fitting portion (288) accepts a threaded nut to secure thepiston rod in the spring bottom end piece (287) between the shoulder andthe nut. A variety of other attachment mechanisms for securing thebottom end of the spring to the piston rod can be employed in alternateembodiments.

While the spring 286 of this embodiment is machined from a single pieceof a titanium alloy, it is expressly contemplated that the spring may beformed by other methods as one piece or as a plurality of pieces.Forming the spring 286 as a one-piece, unitary structure has anadvantage in that the dimensions and shape can be precisely controlledas compared to plastically deforming a wire or piece of rod to attainthe final shape. Moreover, the cross section form of a machined helixcan be square, rectangular or some other shape (e.g. regular orirregular polygon, ellipse, etc.) that advantageously resists transversemotion and so better maintains alignment. Moreover, the dimensions ofthe spring can be controlled so that the mechanical parameters definingthe spring can be well-controlled. Those parameters include, but are notlimited to, the spring constant (force-per-unit-displacement), number ofhelices, the oscillating frequency, the mass, the Q (the ratio of storedenergy to extracted energy per cycle), stresses, strains, etc. In thisembodiment, the spring is set to allow oscillation of the piston/rod atapproximately 110 Hz having a spring constant of 135 N/mm and a nominalpower output of 340 W. The spring in an illustrative embodiment havinggreater power output of 500 W has a spring constant K of approximately407 N/mm, providing a resonant frequency for the MICE generator ofapproximately 163 Hz. This results in an average piston speed ofapproximately 1600 ft/min.

It should be clear that the function of the spring is to store energyproduced by the downforce of the piston after each ignition cycle, andto provide a return upward force for the compression stroke, while atthe same time energy is extracted by the MICE alternator over the entirecycle. The cycle frequency, and hence the power output, of the MICEgenerator is determined by the spring constant. The spring hassufficient energy storage capacity to prevent the spring and attachedcomponents from “bottoming out” due to an imbalance of power output fromthe two-stroke engine and energy extraction by the alternator for anumber of cycles. The spring of this embodiment has exhibited goodspring characteristics up to and beyond its maximum design displacement.A total stroke of approximately 2.5 centimeters (or more) can beachieved in its present embodiment.

It has been observed that the points of maximum stress occur where thehelices join at the pitch angle to the respective top (fixed) and bottom(free) ends 285 and 287 of the spring 286. In order to reduce the riskof stress or fatigue-related failure of the spring 286 at these pointsof stress concentration, each free-end and fixed-end junction includes amilled (or otherwise cut-out using, for example a sinker EDM) rounded“stress-relief” 340 and 341, respectively. The size of the stress reliefis highly variable. In general, it is centered in the jointapproximately between the helix end and the horizontal end piece asshown so that it extends both above and below the joint region. In thismanner, as the end of the helix flexes under compression (and extension)with respect to the end piece, the curved joint defined by the stressreliefs 340 and 341 are free of a small-radius corner that produces highlocal stresses that may serve as a location for crack initiation andsubsequent propagation to produce a fracture. The diameter of the stressrelief 340 is highly variable. In one embodiment it is betweenapproximately 1 and 4 millimeters in radius.

As shown in FIG. 3, the free/bottom end stress reliefs 340 are definedby rounded cuts at each helix junction. They are aligned with verticalcutouts 360 (shown in phantom) located inboard on the bottom end asshown in FIG. 3A. These vertical cutouts 360 further reduce stressconcentrations where each stress relief 340 extends into the planarinner face 366 (shown partially in phantom) of the bottom 287 byallowing the relief to extend radially into the cutout (e.g. a fall-off)rather than simply stopping on the bottom face at given radial distanceas a corner. The radial-outward edge of each cutout is aligned with theinner edge 370 (shown in phantom) of the helix structure.

The upper/fixed end stress reliefs 341 define curving milled slots, asshown, that extend into the fixed end base 285 at an angle slightlygreater that the helix angle with respect to the plane of the inner basesurface 380 (shown partially in phantom). The slots extend radiallyinward a width that is equal to or slightly reater that the inner edge(370) of the helix structure. This helps to ensure that the helixjunction is free of concentrated stress in the with respect to the face380.

The spring 286, piston rod 260 and bottom end 287 ride axially withinthe spring casing 270, which is constructed from machined aluminum alloyhaving a wall thickness of approximately 4 to 8 millimeters (highlyvariable). The top end of the casing 270 includes the flange 276described above that engages the spring top flange 285, which is alsoclosely engaged by the cylinder casing extended flange 268 and thusproduces the alignment between the spring casing 270 and the cylindercasing 203. The spring casing 270 in this embodiment is a semi-openconstruction with three ports (refer to FIG. 4) divided by solid columns288 along its mid-section. This semi-open arrangement reduces weight andis generally optional and/or subject to significant design variationaccording to alternate embodiments.

The lower end of the spring casing 270 includes a flange 289 thatengages a clamping assembly 290 that functions similar to the assembly278, 280 and 282 described above. This clamping assembly 290 axially andradially secures the alternator coil magnet casing 291 to the bottom ofthe spring casing 270. The alternator coil 292 in an illustrativeembodiment is attached via a cylindrical (or part cylinder) standoff orstandoffs 293 to the bottom end 287 of the spring 285. The standoffassembly 293 is secured to the spring bottom 287 using a plurality ofthreaded pins (not shown) that extend downwardly into respective holesin the standoff, and are secured into the standoff holes using epoxy oranother strong, durable adhesive. See FIG. 3A for an illustration ofthreaded holes 390 in the bottom end 287 of the spring 286. The lengthof the standoff ensures that the spring bottom 287 does not bottom outon the inner magnet pole 291 a at maximum piston downstroke. In thisembodiment, the standoff includes circumferential cutouts 293 a thatserve to prevent resistive air compression against the inner magnet pole291 a, vent air around the assembly to cool the structure, and generallyreduce heating of the assembly.

The coil 292 extends axially from the standoff assembly 293 into the airgap 295 of a fixed magnet assembly 294. The air gap 295 measuresapproximately 0.20 inch (radially between the inner magnet surface andthe inner magnet pole 291 a). This air gap 295 includes a clearance ofapproximately 0.015 inch between the coil and inner magnet pole 291 a,and between the coil and magnet assembly 294, in an illustrativeembodiment. The magnet assembly 294 resides in cylindrical well 296formed in the casing 291. The well has a depth, beyond the magnetassembly 294, which is sufficient to allow the coil to drive axiallydownwardly in response the maximum piston downstroke without strikingthe bottom of the well 296. The magnet assembly 294 in according to thisinvention can be arranged in a wide variety of ways. In an illustrativeembodiment, the magnet assembly 294 consists of a plurality ofindividual magnets that define segments of a cylinder that encircles theouter (radially) wall 297 of the well 296, with poles directed axiallywith the resulting the magnetic field directed radially toward the axis262 and therefore through the air gap 295. Thus, the individual windingsof the coil—which is circumferentially-wound with the coil windingsbeing substantially coaxial with the axis 262 and embedded in epoxy—passsubstantially normal to the field direction. This orientation of thefield to the windings maximizes the electromotive force generated bycoil movement. The winding employs 25 AWG wire in one embodiment,composed of a total of 400 windings over a coil Length CL (FIG. 2) of 25mm. In this embodiment, the coil is approximately the same axial lengthas the magnet assembly. The magnets (294) and magnet poles (291, 291 a)can be constructed from a variety of materials. In an illustrativeembodiment the magnets 294 are constructed from high-flux permanentmagnetic material, including, but not limited to, samarium-cobalt orneodymium-iron-boron. The magnet poles are constructed from softmagnetic material such as HIPERCO® 50A or electrical iron.

Alternatively, a coil of increased length could be attached directly tothe spring without use of a standoff. The operation is that as thepiston 204 reciprocates the coil 292 follows, breaking the magnetic fluxlines in the air gap 295 and thereby generating electrical energy fromthe mechanical motion.

Note that it is expressly contemplated, according to alternateembodiments, that the coil can reside in a well or other stationarystructure and that the magnets can be mounted to move axially inresponse to the piston's reciprocation. The term alternator oralternator assembly, as used herein should be taken to include anymechanism that generates electrical power by causing one generatingelement to move axially under power of the piston with respect to theother generating element.

At least one of the leads (not shown) from the coil 292 is (are)insulated from the other conductive materials in the assembly. The leador leads can be routed in any acceptable manner to exit the MICEgenerator structure. Care should be taken to avoid possible failure ofleads due to stretching or cyclic loading. In one arrangement at leastone lead is directed along a spring helix and through the ports in thespring casing near the top end 284. Where two electrically isolatedleads are employed, each lead can be directed along a separate helix.Since the wire diameter will be much less than the cross-section of thehelices, the wire and adhesive are highly compliant and therefore haveminimal effect on the spring motion. In another illustrativeimplementation, one lead is formed by the MICE generator structureitself, which is electrically connected to one side of the coil therebycreating a ground contact to which the power conditioning circuitry isconnected along with the other, electrically isolated lead.

FIG. 4 details an external view of the MICE generator 200 according toan illustrative embodiment, as described with reference to FIG. 2. Theports 410 between columns 288 on the spring casing are more clearlyvisible. The spring 286 is exposed therethrough. In an illustrativeembodiment, the overall length/height. ML of the MICE generator withoutattachments (described below) is approximately 27 centimeters, and themaximum diameter MD in the region of the clamps 420 and 430 isapproximately 8 centimeters. The weight of the MICE generator unit isapproximately 2.7 kg with Hiperco magnet poles, and 3.1 kg withelectrical iron magnet poles.

C. MICE Generator Cooling System

The MICE generator of this embodiment is designed with a relativelytight tolerance between the piston 204 and the wall of the cylinder 206.The cylinder and piston can be expected to undergo thermal expansion andcontraction within a predetermined range as the MICE generatortransitions from a cooler ambient temperature at cold-startup to anormal operating temperature (several hundred degrees hotter, forexample). By reliably regulating the temperature of the cylinder headduring steady state operation, the effects of thermal expansion can bemoderated and, more particularly, the piston and cylinder can be sizedto optimize their relative fit at this desired steady state temperature.In other words, where an unregulated operating temperature may causeexcessive expansion of the cylinder relative to the piston, a moreregulated (lower) operating temperature may reduce relative expansionand maintain it at a desired range. Significantly this range can be setto allow the buildup (without scraping-off) of a combustion-generatedcarbon black (graphite) layer on the piston and cylinder that both sealsthe upper chamber 230 and effectively lubricates the surfaces as theyslide against each other. In this manner it is contemplated that thepiston (also having the above-described hard coating, smooth coatingapplied thereto) is essentially self-lubricating without need of aseparate lubrication oil source.

FIG. 5 details a basic cooling arrangement according to an embodiment ofthe invention. The cylinder head casing 203 is surrounded by a metalcooling head 510 that encloses the casing 203 above the exhaust port210. A simplified muffler 520, similar to that found on a lawn andgarden tool motor is attached to the port using bolts, straps or anyacceptable arrangement. The inlet plenum 220 and an interconnected line522 that delivers atomized fuel air mixture from an ultrasonic atomizerand fuel pump (described below) are positioned below the exhaust port210.

The cooling head 510 is constructed from a thermally conductive metal,such as aluminum alloy. It includes internal tubing or channels 530(shown in cutaway) that encircle the head and pass a stream ofpump-driven cooling fluid (water or another fluid/mixture) from andinlet 532 to an outlet 534. As the fluid moves through the head 510, itconducts heat, generated by combustion away from the head casing. Theinlet 532 and outlet 534 are connected via respective tubing 536 and 538to a conventional heat exchanger (not shown in FIG. 5) that transfersthe cylinder head heat to, for example, an airflow-driven by a fan. Theheat exchanger can reject waste heat in a variety of ways as describedfurther below. A coolant reservoir (not shown) with a capacity ofapproximately 100 ml can also be provided in line with the coolingcircuit described herein.

A temperature sensor 550 (shown in phantom) is provided at one or moreconvenient locations on the casing 203, or another interconnectedcomponent that provide an accurate temperature reading. The sensor 550is interconnected by a line to a controller (not shown in FIG. 5) thatregulates heat exchange, thereby allowing the head to operate within arelatively narrow range of temperatures at steady state. The pump and/orheat exchanger is controlled to regulate the amount of rejected heat,either by regulating the speed of the coolant pump of or the amount ofairflow passing over the heat exchanger.

A basic control procedure 600 is detailed in the flow diagram of FIG. 6.The procedure continually senses the temperature of the cylinder wall oran associated component (step 610). The sensed temperature is comparedto a desired operating temperature (step 620). This can be a range oftemperatures and/or can be dependent upon that particular timing of thesensing step. For example, the system may have one or more lower desiredtemperatures at an early time after startup. Similarly, the desiredtemperature may differ at differing power output levels. A variation ofthis concept is described further below. The controller decides if thesensed temperature is within the desired temperature range (decisionstep 630). If the temperature is within the desired range, then theprocedure 600 continues to monitor the temperature (branch 632 to step610).

If the temperature is not within the desired range (branch 634 todecision step 640), and the temperature is above, the desired range, thecontroller increases cooling at the cooling head 510 (step 650, andcontinues to monitor (branch 652 to step 610). The increase in coolingcan entail increasing cooling fluid pump speed/flow rate and/orincreasing heat exchange at the heat exchanger.

Likewise, if the temperature is below the desired range (decision step640), the procedure calls for a decrease in cooling (step 660) by eitherdecreasing pump speed/flow rate and/or decreasing heat exchange. Theprocedure continues to monitor temperature thereafter (branch 662 tostep 610).

The parameters of size, shape, volume and casing-coverage of the coolinghead 510 are all highly variable. In general, the cooling head should besized sufficiently to allow maintenance of a desired temperature for agiven power output by the MICE generator. In this manner, the relativefit of the piston and head can be better maintained.

While sensing temperature at the cylinder head casing 203 is aneffective, direct technique for determining current operatingtemperature, and thereby regulating cooling, an alternate orsupplementary procedure 700 for controlling cooling is described in FIG.7. Since the MICE generator generally operates at a higher power levelwhen at steady state and/or under load from current draw, the amount ofheat generated by the head tends to increase accordingly at higheroutput levels. To this end, the controller can sense the prevailingoutput level at the output of the alternator or within the powercircuitry (step 710). The procedure 700 determines (via decision step720) whether the prevailing coolant flow or pump speed is at a desiredlevel for the given sensed power output. If the coolant flow is at thedesired level, then the procedure continues to monitor power output(branch 722 to step 710). If the coolant flow is not at the desiredlevel for a given power output, then (via decision step 730) theprocedure either increases pump flow where more power call for morecooling (step 740) or decreases coolant flow (step 750) where lowerpower output calls for less cooling. The level of heat exchange at theheat exchanger can also be regulated according to alternate embodiments.

It is contemplated that attaining appropriate head casing temperaturecan be desirable prior to startup. This occurs in part through theenergizing of the glow plug 232 by the controller. The heat generated bythe glow plug causes the upper chamber 230 to heat, and also transmitsheat to the surrounding casing. However, significantly greater heatingof the casing to a temperature closer to the desired operatingtemperature can be achieved by providing a supplementary electricalresistance heater (wires 560, shown in cutaway) to the cooling head 510,that operates prior to and during startup to quickly heat the casing 203to a temperature that brings the piston and casing closer to their finalthermally expanded sizes. Alternatively, an electrical resistanceheating assembly (for example, a nichrome wire coil) can be provided inline with the heat exchanger so as to heat the liquid stream to therebyheat the cooling head 510 and attached casing 203. Appropriatecontroller programming can be provided to activate the resistanceheating assembly during a startup sequence and thereafter deactivatethis “block heater” when a predetermined temperature and/or power outputis attained.

D. Control of Air/Fuel Temperature at MICE Generator Intake Plenum

It is recognized that use of low-volatility fuels, such as JP-8,typically requires a significant degree of atomization to achieveadequate combustion at ambient (or slightly elevated) inlet temperature.The fuel system avoids the use of costly and complex fuel injectioncomponents by providing a sealed plenum 220 that defines a vaporizationspace around the intake port 212. As shown in FIG. 5, the plenum 220 issupplied by an enlarged diameter hose or tube 522 that carries a mixtureof fuel and air from an atomizer. A conventional ultrasonic atomizerthat receives fuel from a source via a pump, and mixes the fuel with airfrom an intake, is provided (see below). The input fuel mixture isdispersed into small liquid droplets when it reaches the chamber of theplenum whereupon it evaporates at the elevated temperature and residencetime provided by the inlet plenum. It is then drawn through the intakeport 212 to eventually rise into the upper combustion chamber 230, viathe transfer port 222. To ensure volatility of the mixture, particularlyat startup, the plenum can be heated. FIG. 8 shows an internal plenumheater composed of a coil of electrical resistance wires 810 that arewrapped directly around the head casing 203 in the interior space of theplenum. This arrangement advantageously heats the head simultaneously toelevate the head temperature prior to startup. Alternatively (oradditionally), wires can be provided to the outer wall 820 and/oranother location on the plenum or within the plenum space 218.

In general, the heating of the plenum space 218 is controlled by thecontroller and occurs at least until a sufficient time after startup haselapsed, the head temperature has attained a predetermined level and/orthe power output has achieved a certain level. In some embodiments,plenum heating occurs continuously at some level throughout operation toensure appropriate fuel/air volatility. In fact, control of plenumheating (or heating of another portion of the fuel-delivery system) canbe employed to regulate power output by controlling the inlet chargedensity. FIG. 9 describes a procedure 900 for controlling power outputusing plenum heating. The controller senses the state of power outputand/or load (step 910) and compares this value with the needed poweroutput or load (step 920). If power is at the desired level (decisionstep 930), then the system continues to sense and compare (steps 910 and920 via branch 932). Conversely, if there is an imbalance between neededoutput and existing output (decision step 940 via branch 934), then thecontroller determines whether the present output is above or below theneed. If the power output is above the need, then plenum heating isincreased (step 970) to reduce the density of fuel/air and thus the massflow rate of reactants delivered to the two-stroke engine, and thecontroller continues to sense and compare (steps 910 and 920 via branch962). Conversely, if power output is below the need, then the plenumheating is reduced (step 960) to increase the density of fuel/air, thusincreasing the mass flow rate of reactants to the two-stroke engine.This control scheme presupposes that at all times the level of airpreheat is sufficient to vaporize the fuel droplets prior to thecompletion of the compression stroke to permit efficient combustion. Thecontroller then continues to sense and compare (steps 910 and 920 viabranch 972).

Since, at various times the plenum requires heat and the cooling headeither requires heat (startup) or may need to reject heat (steady stateoperation), it is contemplated that an integrated heating and coolingsystem using moving fluid can be provided in an illustrative embodiment.FIG. 10 details a somewhat schematic side view of the area of thecylinder head casing 203 with a cooling head 1010 similar to the head510 described above and an intake plenum 1020, also similar to theplenum 220 described above. The Cooling head 1010 and the plenum 1020each include an internal coil of fluid lines or conduits 1012 and 1022,respectively. The coils can be mounted externally, or at anotherposition so long as they act to transmit heat between the underlyingstructure and the fluid, which they carry. The coils in each structureare connected at one end by a linking conduit 1030 that routes a flow offluid (arrow 1032) therebetween. The coils 1012 and 1022 are eachconnected at an opposing end by a fluid pump assembly 1040, which can beplaced at a location relative to the MICE generator. A remote heatexchanger 1046 can also be provided to remove excess waste heat, using acontrollable fan 1048 where appropriate. The heat exchanger wouldtypically operate at high output states and or when operating in hotclimates.

The pump assembly 1040, including an interconnected electrically drivenpump 1042 is interconnected with the controller (not shown in FIG. 10).The pump operates to selectively move fluid between the coils 1012 and1022 when the temperature sensor in either the cylinder head (sensor1050) or plenum (1052) reports a predetermined condition (too hot, toocold, just right). In this manner, during steady state operation (poststart-up) heat generated by the cylinder head is carried away via thecooling head coil 1012 and delivered to the plenum 1020 when needed.Excess heat, not needed to heat the plenum is exhausted through the heatexchanger. As noted above, one parameter by which plenum heat isregulated may be the desired power output. This parameter can becombined with the plenum temperature sensor 1052 to provide thecontroller with a decision on the amount of heat to deliver to theplenum.

During cold-startup, all components are typically at, or near, ambienttemperature. As discussed above, a mechanism for warming the cylinderhead 203 and plenum is desirable. In this embodiment, an electricalresistance heater 1060, responsive to the controller is provided in linewith the fluid conduits, externally of the MICE generator. This heatercan be provided at the heat exchanger or at any convenient locationalong the fluid path that affords rapid and efficient heating of thefluid stream to a desired temperature. The heater is operated inconjunction with the pump to deliver heated fluid to both the coolinghead and the plenum until a timer and/or the temperature sensor(s) 1050and/or 1052 indicate a sufficient startup heat has been attained. Theheater's output is then shut off or reduced and startup is allowed toproceed. Alternatively, a separate electrical heater can be provideddirectly to either (or both) of the cooling head and plenum to be usedat startup, after which the fluid-based heat-transfer system of FIG. 10takes over. As a further alternative, any of the arrangements describedherein (e.g. fluid-based heating, resistance heating, etc.) can routeheat directly to intake air, prior to mixing with fuel. Additionalheat-transfer arrangements are described below with reference toalternate embodiments.

E. Sound Dampening

It has been recognized that, without acoustic dampening, the MICEgenerator according to various embodiments contemplated herein iscapable of producing sound pressure measurements in excess of 112 dB atapproximately 1-foot distance therefrom. This is an extremely loud soundoutput that would render the MICE generator unsuitable for most fieldapplication, and possibly harmful to users' hearing. By providingeffective silencing and dampening to the MICE generator and the overallgenerator system packaging, the effective sound pressure can be reducedto less than 55 dB, making it useable for a wide variety of applicationswhere relatively quite operation is sought.

FIG. 11 details a basic configuration for isolating the MICE generator200 according to an illustrative embodiment. In this embodiment, aninternal muffler (see, for example, muffler 520 in FIG. 5) is providedin proximity to the exhaust port of the MICE generator. As describedbelow, in certain alternate embodiments, the muffler can be providedremote from the MICE generator and interconnected via a sound-dampenedexhaust conduit. The MICE generator is mounted on a mounting plate 1110sufficient to support the weight of the MICE generator and the acousticenclosure (constructed from ⅛ to ¼-inch aluminum, for example). Theplate 1110 supports an outer enclosure 1120 that is generallycylindrical in shape in this embodiment (other shapes can be employed),with an enclosed top end 1122. In one embodiment, the shell 1124 of theenclosure 1120 is constructed from sheet steel having a thickness ofapproximately 0.03-0.05 inch. The exact composition and thickness of theenclosure shell 1124 is highly variable and determined by the acousticdampening and weight requirements. In this embodiment the overall outerdiameter DE of the enclosure is approximately 6.5-9 inches. The overallheight HE of the enclosure is approximately 16-18 inches. The dimensionsare highly variable, based upon the size of MICE generator attachedcomponents such as the cooling head and the muffler. Both the interiorand exterior of the enclosure may be wrapped with a thin layer (⅛-¼inch, for example) of acoustic foam 1130 and 1132, respectively. Thefoam can include heat shielding foil (not shown) on the interior and/orexterior where in proximity to a heat source, such as the muffler. Ingeneral, best performance is attained when both the muffler and theinlet pipe are tuned to the particular sound signature of the enclosure1120 using well-known tuning techniques based upon formulae and/or trialand error.

In alternate embodiments, a separate mounting plate can be omitted andthe shell 1124 of the acoustic enclosure can be mounted directly on thefloor of an external package enclosure (see external packages in FIGS.14-15 below) along with the MICE generator. For the purposes of thisdescription, the floor upon which the MICE generator and/or shell issupported can be termed generally a “support surface” and the term“plate” can otherwise be taken broadly to include unitary and integralbase structures that are part of the external enclosure of thegenerating system unless termed a “separate” plate.

The inlet tube 1140 for fuel/air mixture is routed through anappropriately sized (closely-fitting) hole in the enclosure. The holecan also route various electrical and fluid conduits (collectively shownas lead 1142), such as the alternator leads, temperature sensor leads,the glow plug lead, and other control cables. In this embodiment,exhaust is expelled via six or more 1-inch diameter holes 1150 formed inthe top 1122 of the enclosure. The number, size and placement of theholes are each highly variable. In general, each hole 1150 is coveredfrom the inside by a porous plug (see plug 1160) constructed from porousglass fritted or ceramic material approximately 8-12 millimeters inthickness. The plugs in this embodiment have a pore size of between10-20 microns, thereby delivering a flow resistance of approximately6.6×10⁻⁴ atm/(cm/s) for a flow area of approximately 30 cm²(corresponding to a 4-inch H₂O pressure drop for a flow rate of 40slpm). Such flow resistance provides effective dampening withoutexcessive back pressure within the enclosure.

As described below, the MICE generator 200 and enclosure 1120 aremounted within an external package with further sound dampening.Appropriate venting of exhaust from the enclosure plugs/holes 1150/1160to the environment is provided in the external package.

F. Vibration Isolation

The inline piston-spring-alternator coil employed in the MICE generatoraccording to this invention generates substantial oscillatory motionwithin the overall casing generally along the axial direction thisvibration is capable of generating significant sound emission betweenthe MICE generator and its supporting base, even absent anycombustion-generated sound. FIG. 12 details a vibration-isolationarrangement in which the MICE generator 200 is provides with threeequally circumferentially spaced L-shaped base “feet” 1210. The numberand placement of feet about the MICE generator's circumference is highlyvariable. In this embodiment the feet 1210 are essentially clamped tothe alternator casing 291 between the clamp 290 and bottom 1220 of thealternator casing 291. A variety of arrangements for feet, includingthose that are unitary parts of the casing are expressly contemplated.In general, they should be securely attached to the MICE generator 200without any movement between the feet and the MICE generator.

The feet 1210 each rest on one or two soft springs 1230, which aremounted on the base plate 1110. In this embodiment, the springs 1230each are conical tapering from a larger-diameter coil 1240 adjacent thebase plate 1110 to a smaller diameter coil 1250 adjacent to eachrespective foot 1210. This design affords good stability and resistanceto transverse shear. The springs allow free vibration of the MICEgenerator along the axis (double arrow 1260), in line with pistonmotion, but the springs 1230 are sufficiently strong to prevent the feet1210 from bottoming on the base plate. In actual tests, this approachhas essentially eliminated transmission of vibration from the MICEgenerator to the external package.

FIG. 13 shows an example of flexible lead placement as part of thevibration isolation solution of FIG. 12. According to an illustrativeembodiment, the various leads and intake tubing (1142 and 1140) can be“staked” at two locations using clips, ties or similar fasteners 1310and 1320. In this example, one fastener secures the lines 1140, 1142 atthe side of the MICE generator casing (on a foot 1210) in this example.Any suitable location on the MICE generator above the springs 1230 canbe employed. The other fastener 1320 stakes the leads 1140 and 1142 nearthe outlet hole, leading out of the enclosure (removed for clarity) onthe sturdy base plate 1110. The region 1330 above the fastener 1310 isessentially free of flexure or bending, as it is fully contained alongthe solid case of the MICE generator between the fastener 1310 andinterconnections to various parts of the MICE generator. Similarly, theregion 1340 extending out from the base plate fastener 1320 is free ofany bending or flexure. The area of leads between the fasteners 1310 and1320 is long enough and oriented so that is flexes, in essence, as asolid body as the MICE generator oscillates on its springs 1230 withrespect to the base plate. Thus, the long solid body-like lead sectionis less likely to fail over the long term due to fatigue, etc.

To afford further support to the oscillating MICE generator in alternateembodiments, appropriate springs (not shown) can be provided between thetop of the enclosure or package and the MICE generator, which furthersupport and isolate the MICE generator from vibration and lateral shear.Likewise, radially or laterally mounted springs can be provided betweenthe casing of the MICE generator and the sidewalls of the enclosure toafford greater lateral support. Alternatively, springs mounted at someangle (at 45 degrees relative to the base, for example) can provide bothaxial and lateral support, thus replacing a combination of axial andradial springs.

G. Arrangement and Packaging of Generation System Components

The MICE generator of the above-described embodiment is packaged as partof an overall power-generation system that is relatively lightweight andportable—for example, weighing approximately 20 pounds and sizedapproximately 14×12×7.5 inches in one version. Within this relativelythis small “external” package is the capability of generating acontinuous electrical output of 500 W or more. The packaging takes intoaccount sound and vibration dampening and also provides adequateaspiration of fuel, exhaust ejection, thermal regulation, automaticstartup capability and speed/output regulation.

An exemplary packaging arrangement is shown in FIG. 14. This packaginglayout is desirable in instances where an external fuel source andexhaust system are provided, such as in a land or water-going vehicle. Amore-self-contained version of the external package will be describedbelow. The arrangement of FIG. 14 consists of an external packageenclosure 1410. This enclosure 1410 is constructed from metal (typicallysheet steel or aluminum), polymer or a combination of materials. Theexternal package 1410 encases a sound-dampened MICE generator acousticenclosure 1420 with MICE generator and cooling, exhaust and sensingcomponents therein, similar or identical to that described above.External dampening foam surrounding the acoustic enclosure 1420 has beenomitted from the illustration for clarity but is typically present in anillustrative embodiment. The acoustic enclosure includes inlets andoutlets formed therethrough to allow passage of external cooling tubing1430, 1432, a fuel/air mixture inlet 1434 and an exhaust outlet 1436. Anelectric fan 1440 with an external port 1442 is provided to draw incooling air. An appropriate outlet (not show, can be provided along aside wall at a location opposite. This fan allows combustion make-up airto enter the housing and generally cools the electronic components andheat exchanger within the MICE generator cooling loop. Note, in analternate embodiment, the inlet 1434 can be provided near the base 1110of the acoustic enclosure 1420 to take advantage of the staking of leadsbetween the MICE generator and base 1110 as described above, referencingFIG. 13.

The fuel-delivery system consists of an inlet fuel line 1450, fed froman external source. An internal fuel tank of appropriate size can beprovided in an alternate embodiment. The fuel line 1450 leads to asolenoid fuel pump 1452. This pump is controlled by control circuitrythat can be located in a controller enclosure 1454 that also containsappropriate AC/DC power conditioning electronics. The pump feeds fuel toa microelectro-mechanical systems (MEMS) fuel atomizer 1456 commerciallyavailable from a variety of suppliers. Other types of atomizers(ultrasonic, for example) can be used in alternate embodiments. Theatomizer is controlled by associated circuitry 1458 through leads 1460.The circuitry communicates with the controller 1454 through leads 1462.An air inlet 1457, shown covered with a porous filter medium (bronze,for example), is provided in connection with the atomizer 1456. Atomizedair and fuel mix at the junction therebetween and form the vaporizedfuel/air mixture entering the MICE generator intake plenum. In thismanner, no complex fuel injection is needed, even when employinglow-volatility diesel-like fuels.

In this example, porous plugs for venting exhaust gasses are omitted. Assuch the exhaust is vented, either directly from the MICE generatorexhaust port or through a muffler within the enclosure, to an externalexhaust tube 1436 constructed from, for example stainless steel tubingof between ¾ and 1½-inches in diameter. The tubing is overlaid withacoustic foam 1470 (and thermal insulation where appropriate). Thediameter of the tubing can be selected, in part, to provide a tunedacoustic signature for a given steady-state level of power output. Theoutlet 1472 of the exhaust tubing 1436 is directed to a vehicle exhaustheader or external muffler in this embodiment.

The MICE generator within the enclosure 1420 is cooled by a coolingsystem that includes a cooling pump 1474, driven by an electric motor1475 that is powered through the control electronics 1454 (via leads1476). The pump pulls fluid through the tube 1432 into the cooling headof the MICE generator. It draws fluid from the tube 1478 that passesthrough a reservoir 1480 also connected to the cooling head tube 1430.In one embodiment a flow rate of approximately 250 ml/min should besufficient. A heat exchanger 1482 is provided internally in thisembodiment between tubes 1432 and 1432 in the fluid circuit. The heatexchanger can be sized and positioned to present as large a surface areato the fan-driven (1440) airflow as needed. Alternatively, the heatexchanger can be external of the package enclosure 1410. Where externalcooling is employed, the cooling system can also be interconnected to anappropriate external cooling system, such as a watercraft coolingcircuit or vehicle cooling system.

The external package 1410 supports a storage battery 1486 consisting ofa cluster of rechargeable batteries. Batteries are needed to supportstartup operations as described generally above. In particular, intakeand MICE generator preheat operations may require temperatures aroundthe intake and head to be elevated by approximately 100 degrees C. fromambient temperature. In addition, startup is achieved (described furtherbelow) by energizing the glow plug, and selectively powering thealternator coil to oscillate the piston (since the alternator can beused in reverse as a motor) until continuous combustion is achieved. Itis estimated that the overall power requirement to achieve startup inapproximately one minute is about 320 W for a MICE generator in the300-500 W power output range. An array of six high-qualitynickel-metal-hydride (NiMH) battery packs, each dischargingapproximately ⅙ of their total energy during startup, should besufficient to ensure reliable operation. Such batteries would have atotal weight of approximately 0.4 kg (assuming an energy density of 80W-hr/kg) and a volume of approximately 100 cc. Other types of energystorage are expressly contemplated, including capacitors, lithium-basedbatteries, and lead-acid batteries where appropriate. Similarly, incertain vehicle applications, startup power can be obtained fromexternal power systems or manually-cranked systems.

The control and power conditioning circuitry is contained in thecircuitry enclosure 1454. A dashed line 1490 represents the variouspower, control and sensing leads that pass between the control circuitry1454 and the MICE generator through appropriate ports(s) in the acousticenclosure 1420. The circuitry enclosure 1454 can be electromagneticallyshielded where appropriate and can be sealed to prevent infiltration ofmoisture that may damage components. The controller for systemoperations can consist of a microcontroller, microprocessor, programmedlogic array or a combination of such components. The controller isinterconnected with various power and temperature sensors as describedherein and can contain appropriate timers to regulate functions, such asstartup preheat, etc. The controller interacts with power conditioningcircuitry that receives raw AC output from the alternator and convertsit to a desired voltage and current type (AC or DC). Since the output inthis embodiment (highly variable according to alternate embodiments)produces 24-28 VDC, the alternator output is first routed through arectifier (described below) consisting of a diode bridge, inductor andtwo capacitors. The resulting DC current is then stabilized to 24-28volts using a converter module that can be based around a ModelV300A24C500B DC-DC converter available from Vicor of Andover, Mass. Thismodule is sized for approximately 500 W and will deliver 24-28 VDC froman input voltage (at the alternator) of between 180 and 375 V. The sizeof the over-all package that houses the power conditioning circuit isapproximately 3×4×7 inches and weighs approximately 1 kg in anillustrative embodiment.

The external package enclosure includes connections/outlets that allowinterconnection of power leads from a device to the generating system. Aside panel 1492 is electrically connected to the circuitry 1454 andincludes one or more appropriate outlets (not shown) for linking thepower lead to the generating system. Likewise, this panel 1492, oranother panel on the exterior can include one or more indicators ormeters (analog, LCE, LED, etc.) that report system status, power output,warnings and/or other key information. A start button can also beprovided.

It should be clear that the placement and size of components within theexternal package is highly variable. The overall arrangement may bebased, in part upon the mission, for which the system is designed.Briefly, FIG. 15 shows an alternate arrangement of components for afully self-contained and portable version of the system. The externalpackage enclosure 1510 can be constructed from metal or durable polymerand include internal sound-dampening material (foam, not shown). TheMICE generator is contained in an acoustic enclosure 1520 as describedabove. In this version, a tuned, internal muffler (not shown in FIG. 15)is contained within the acoustic enclosure 1520 and vents exhaust(arrows 1530) into the external package space via porous plugs 1532. Air(arrow 1544) is passed through the external package enclosure space byan electric fan 1542 that drives warmed air (arrows 1540) out of thespace through an air intake located at the bottom rear as shown (or atanother position) on the enclosure 1510. The fan can also be used tovent exhaust as shown, or a separate muffler outlet can be used. The airpasses over an internal heat exchanger 1550 that is connected to areservoir and pump (not shown), feeding coolant to the MICE generatorthrough the acoustic enclosure 1520. A fuel tank 1560 with a fill cap1562 is located at the top of the housing. The fuel is driven into anatomizer 1566 that feeds the MICE generator a vaporized fuel/airmixture. A battery 1570 is provided for startup and control/powerconditioning circuitry is contained within an enclosure 1580. A panel1590 with power connections, status meters and switches is located on aside face, but can be located at any convenient position (or positions)on the enclosure 1510. The panel communicates with the circuitry 1580via leads (dashed line 1592). A carrying handle 1594 is provided at anappropriate balance point at the top end of the enclosure 1510 for easeof portability. As noted above, an overall package weighing only about20 lbs is contemplated, rendering it easily portable with one or twocarrying hands by a single individual.

H. Startup Sequence

Having described generally the components employed to effect startup ofthe MICE generator, reference is now made to FIG. 16, which details anexemplary startup procedure 1600 according to an illustrativeembodiment.

Clearly, the first step is to switch the generating system to start(step 1610). This action directs to control circuitry to energize theelectric preheater used to warm the air intake (plenum) and cylinderhead (step 1620) when low-volatility fuels are used. This step can beeliminated if gaseous fuels such as propane or butane are used. The glowplug may also be energized at some point within this step, dependingupon how much heat can be derived from the plug to warm the head and thecombustion chamber. The power to heat the intake and head is derivedfrom the storage batteries described above. These batteries arerecharged by conventional charging circuitry operatively connected tothe power output circuit during steady state runtime.

After the control circuitry detects that sufficient preheat has beenapplied, either through use of a timer or a temperature sensor at anappropriate location within the intake and/or cylinder head, the controlcircuitry then activates the atomizer and fuel pump at a minimal setting(step 1630). At this time, the control circuit also directs power intothe alternator coil of the MICE generator. This effectively converts thealternator into a linear motor that oscillates the piston (1640). Ifgaseous fuels are used (such fuels being contemplated for use inalternate embodiments of the MICE generator configuration describedherein with conventional changes to allow gaseous fuel intake), thisstep is initiated immediately after the MICE generator system has beenswitched to start. The direction, amplitude and frequency of the currentare chosen so that the coil causes a pulsation in piston shaft thatdeflects the spring and causes it to rebound, thereby forcing the pistonbetween its bottommost and topmost positions. This selectively opens andcloses the exhaust, inlet and transfer ports while vaporized fuel beginsto enter the upper piston chambers. The glow plug is fully energized atthis point (if not previously energized as noted above) to effectcombustion when fuel and air are compressed at the topmost position.

As combustion begins to occur, the control circuit increases the fuelflow as needed to support independent piston operation (step 1650). Forliquid fuels, the control circuit increases the atomizer and fuel pumppower to admit more fuel, the control circuitry now detects power outputfrom the power circuitry (step 1660). If power output exceeds batterydrain by less than approximately 60 W (decision step 1670), then thedriving of the alternator coil continues (branch 1672) until thepredetermined output level is detected. When power exceeds thepredetermined level (branch 1674), the control circuit disconnects thebattery pack from the alternator coil (step 1680), and the system enterssteady state operation (step 1690), gradually transitioning from unevenoperation to relatively even, steady output as fuel flow is adjusted toa steady level and MICE generator operational temperature reaches arelatively constant value. At some point, the preheater is deactivated,as sufficient latent heat exists in the intake and head, and can besupplemented by fluid-driven heat exchange systems as described herein.Control of temperature and fuel flow are regulated on an ongoing basisby the controller based upon power drain, sensed temperature and otherparameters described herein and generally contemplated for controllingoperation of a combustion engine.

Briefly, deliberate shutdown of the generating system occurs when ashutoff signal is transmitted via a switch to the control circuitry. Inan illustrative embodiment this causes the fuel pump to shut down,stopping fuel delivery to the MICE generator and allowing any fuelremaining in the inlet system to be consumed before stoppage occurs.Subsequently other components are shut down as the alternator coil nolonger delivers current. In the case on inadvertent shutdown (stalling)the circuit may undertake one or more attempts at an automatic restartprocedure (similar to FIG. 16). If a certain number of attempts fail,the system then indicates a problem condition (or lack of fuel).

I. Dual Clipper Circuit and Overstroking Considerations

As discussed above, in steady state operation the alternator coilproduces an AC (approximately 110 Hz) power output in the range ofapproximately 180-375 volts in this embodiment. The output voltage levelmay vary significantly between cycles and is dependent upon theamplitude of the piston stroke. There are no physical limit stops innormal operation, restricting the stroke in this embodiment, and thus,the relative force of combustion versus resistance applied by the MICEalternator and energy storage by the spring sets the appropriate limit.

Accordingly, FIG. 17 details a circuit diagram 1700 in which thealternator coil 1710 outputs alternating current when switched by theswitch S1 to a rectifying diode bridge D1-D4. An inherent 6-ohm(approximate) coil resistance is represented as the resistor R1. Thisresistance is appropriate for a coil designed for electrical iron magnetpoles generally contemplated for use in the alternator of thisembodiment. The diode bridge D1-D4 delivers DC current of varyingvoltage between the positive output (+) and ground GND. Two clippercircuits are also interposed between (+) and GND. These consist of a“hard” clipper circuit 1720 that is adapted to address overstroking anda “soft” clipper circuit 1730 that addresses electronic load control.The switch S1 is closed to provide the loads of the two clipper circuitsto the alternator once the MICE generator is running on its own powerand the startup batteries 1712 are disconnected. This can beaccomplished automatically, as discussed above, by triggering the switchS1 based upon excess power greater than (for example) 60 W. Note that acontroller 1714 is provided in connection with the batteries 1712 toselectively connect and disconnect them and to drive the oscillation ofthe alternator coil 1710 during startup at the resonant frequency of theoverall mass-spring combination of the MICE generator.

A current compensation circuit 1740 consisting of transistors T1 and T2and associated resistors R3 and R4 (16 K-ohm and 27 K-ohm, respectively)interconnect with each of the hard clipper 1720 and soft clipper asshown. An output current meter circuit 1750 is also provided in thisexample. It can be omitted in alternate embodiments.

In this embodiment each clipper circuit 1720, 1730 is adjusted manuallyby an associated rheostat 1722 and 1732, respectively. Each rheostatallows the load of the given clipper to be adjusted to either limit ormaintain at the voltage in a predetermined range (for example, 250-253V). The voltage and current flow and current through the circuit ismonitored, as such. If the measured voltage level in the hard clipper1720 deviates significantly above the exemplary set voltage of 250-253V, then this indicates an overstroking condition and the prevailing loadon the alternator increased by the depicted IRFP440 MOSFET 1770, therebyrestoring the desired voltage range through the hard clipper 1720. Thiscan be accomplished automatically by digital or analog controllers thatlink with an appropriate variable resistive component in the place ofthe rheostat 1722.

Likewise, if the measured voltage level of the soft clipper 1730deviates significantly from the exemplary 250-253 V, then the load isout of balance with the alternator output and the soft clipper 1730changes and rebalances the load through the action of the MOSFET 1770 torestore the exemplary voltage level. The rheostat 1732 can also be setor readjusted automatically by digital or analog controllers that linkwith an appropriate variable resistance component in place of therheostat 1732. Note that the soft clipper circuit 1730 includes a 10K-ohm variable resistor R5 in this embodiment that enables the“softness” of the load regulation to be varied within predeterminedbounds. This allows for more-aggressive or more-relaxed response to aload imbalance. In practice, a set level of softness may be preset byappropriate resistors, or can be applied variably by the controller fordiffering overall power levels and/or operating conditions.

As shown in FIG. 17, the paired 12-volt Zener diode D5 and 33 K-Ohmresistor R6 serve to respectively, limit the voltage produced on thecontrol terminal (gate) of the MOSFET 1770, and to set the currentsdrawn through the series connected multiple Zener diodes (exemplified bythree 51-volt Zener diodes D6 connected in series and four 12-volt Zenerdiodes D7 connected in series) to an optimum value for the Zener diodes.The MOSFET 1770 is one embodiment of a power-controlling device whichcan be dynamically adjusted by a voltage or power-measuring system tobalance the power drawn from the alternator.

In an alternate embodiment, the MOSFET 1770 is employed as a variableload that can be varied to extract power over the entire cycle, ascontrasted with the clipper circuit that removes power from the cycleonly when the voltage exceeds a specified value. This approach mayprovide for more-uniform and effective power extraction and load controlthan the clipper circuit in certain implementations, thereby reducingthe electrical losses and reducing the stress on the alternator coil,and its attachment to the spring.

J. Alternate Intake-Heating Arrangements

As discussed above, variety of heat-exchange and intake-heatingarrangements are contemplated. FIG. 18 details a further intake heatingarrangement that can be used discretely or in conjunction with the MICEgenerator cooling head 1810. Because the vaporization of fuel/airmixture benefits from a warm intake chamber, it is contemplated thatfurther intake heat can be obtained from applying a fluid jacket and/orcoil 1812 to the exhaust outlet/muffler 1820. In a basic arrangement,the fluid is transported by an electric pump 1830 through thejacket/coil 1812 via a reservoir 1840. The speed and operation of thepump is controlled the controller based upon prevailing inlettemperature. This temperature is derived from a temperature sensor 1850located within the inlet flow. A heat exchanger (not shown in FIG. 18)can be provided to remove excess heat when desired. The size and shapeof the exhaust coil and jacket is selected to allow sufficient heat tobe presented to the inlet area 1860 during steady state operation. Theinlet area is wrapped in sufficient lengths of fluid tubing to transferthe needed amount of heat. Note that both the intake plenum 1862 (seedashed line tubing 1864) and inlet port area 1866 (and leadtube/atomizer outlet) can be heated to achieve the desired inlettemperature.

The cooling head 1810 can also be interconnected to the fluid flow asindicated by the dashed lead lines 1870. The head 1810 can provideadditional heat to the inlet as described above, and is thereby cooledwhen needed to maintain the appropriate temperature level for propercylinder-to-piston fit. Valves and heat exchangers can be interposedbetween the head leads 1870 and the flow to ensure that the inlet is notexcessively heated. A temperature sensor 1872 within the region of thehead 1810 determines the appropriate level of flow therethrough.

In an alternate embodiment, shown in FIG. 18A, heat can be transferreddirectly from the exhaust to the inlet air mixture by placing a sheath1880 (shown in cross section) over the exhaust muffler 1820 and/orexhaust line 1821 through which all, or a portion, of the inlet airmixture flows (arrows 1881) before entering the inlet plenum 1862 (arrow1883). A valve 1882 controls the relative fraction of inlet air thatflows over the exhaust components (arrows 1886), and is heated thereby,and the fraction that flows (arrow 1888) directly to the inlet plenum tomix with the heated air. The pressure differential to drive the inletair flow can be provided by the natural aspiration of the two-strokeengine, or alternately by a separate blower or fan (not shown). Thevalve 1882 can be actuated electrically, using a servo, stepper motor orsimilar mechanism in communication with the controller and responding tothe temperature sensor 1850 or another parameter, such as power outputfrom the alternator.

K. Alternate Piston Spring Assembly

The basic design of a piston spring detailed in FIGS. 2 and 3 is adaptedto compress and expand from rest between each of the bottommost andtopmost stroke positions respectively. As such, the spring is designedto undergo both tension and compression which requires in turn that thespring ends be integral with the end plates. Given the high degree ofcyclically applied force experienced by the spring and the stressconcentrations resulting from the integral structure, a spring thatundergoes only tension or compression exclusively, and is physicallyseparate from the end plate structure, is desirable. FIG. 19 details aquad spring assembly 1910 that can be mounted in a spring casing similarto the casting 270 described for FIG. 2 above. The spring assembly 1910consists of four similar single-helix springs with a simple coil design,1920, 1925, 1930, and 1935, provided in line and concentrically witheach other. In essence each spring in a respective spring pair 1920,1925 and 1930, 1935 is intermingled with the other spring in the pair toachieve the equivalent geometry of a double helix arrangement. Thesprings can be constructed using circular-cross section wire stock inthis embodiment.

The springs 1920, 1925, 1930, 1935 each have two opposing free ends 1921(as opposed to one free and one fixed end as provided in the spring 286of FIGS. 2-3 above), which are secured to a central base 1940 and a pairof opposing end plates 1922 and 1932 using recessed pockets in thecentral and end plates, or by other means. The pockets permit a rockingor rolling motion of the spring ends 1921. The end plates 1922 an 1932are attached to the spring casing (not shown in FIG. 19). The springseach bear upon a central base 1940 in a manner so as not to impart abending force to the plate that causes the plate to tilt relative to thepiston axis. The central plate 1940 is fixed to the piston shaft 1950.The bottom end of the piston shaft is operatively connected with amoving alternator coil assembly (not shown in FIG. 19) similar inconstruction to the coil 294 described for FIG. 2. The coil differs inthat it moves under action of the shaft without connection to the bottomend of the spring itself.

The illustrated arrangement of four stacked, fixed springs 1920, 1925,1930 and 1935 with a floating base 1940 therebetween enables the lowerspring 1930 to compress on the downstroke while the upper spring 1920relaxes but remains in contact with the central base (leaving the upperspring under slight compression at the end of the stroke). Likewise, thepiston upstroke causes the upper spring 1920 to compress while the lowerspring almost fully uncompresses while remaining in contact with thebase 1940. Hence, this arrangement allows each spring 1920 and 1930 toact mainly in compression, lessening the cyclic load that each springmust endure. This also allows inexpensive, simple coil springs to beused in place of an expensive machined multiple helix spring withintegral ends.

The cross sectional dimension of the helix, spring material and overalldiameter are each highly variable. These parameters should be selectedto provide an acceptable safety factor against fatigue failure and toensure sufficient applied force against the piston stroke. It isexpressly contemplated that the springs can be dissimilar in length,diameter and/or helix-cross section in alternate embodiments. Likewise,the arrangement of stacked, concentric springs as shown in FIG. 19 canbe substituted with another acceptable arrangement, such as two or morenested springs. To this end, it is contemplated that any of the springarrangements shown herein including a combined compression and tensionspring like that of FIG. 2 can include two or more nested springs eachapplying a force through some or all of the piston stroke. Such anarrangement can be used to provide a stronger resistance force in theevent of overstroking, for example.

L. Deployment of an Exemplary MICE Generator-Based Generating System

FIG. 20 details a schematic representation of exemplary applications fora MICE-based generator 2010 having the rated power output contemplatedherein. Not all components shown are necessarily connected concurrently,or in concurrent use due to output limitations. Nevertheless, it iscontemplated that radio equipment 2020, computers 2030, external batterychargers 2040, interior and exterior lights 2050 can all beinterconnected with, and operated by, the generating system 2010. Othertypes of equipment 2060 can also be interconnected including, but notlimited to, electric heaters, night vision scopes, global positioningand navigation devices, signaling devices, refrigerated coolers andother appliances operating at less than or equal to the rated generatoroutput. Using a 1.5 liter fuel tank, the generating system is estimatesto provide rated power demands for more than four hours.

It should be clear that the generating system of this invention offers areliable, relatively efficient and highly portable solution to fieldelectric requirements. With appropriate modifications, it is expresslycontemplated that the rated power output can be scaled up or down tosupply particular needs outside those described herein.

The foregoing has been a detailed description of illustrativeembodiments of the invention. Various modifications and additions can bemade without departing from the spirit and scope thereof. For example,the type of fuel employed can be widely varies and alternate fuelsources including gaseous sources (at ambient temperatures andlow-altitude pressures), biologically based fuels (e.g. biodiesel), andcombinations thereof can be employed. Likewise, the materials employedfor any aspect of the invention are highly variable and compositesand/or polymers can be substituted where practical to reduce weightand/or increase durability. It should also be noted that various termsused herein, such as “top,” “bottom,” “upper,” “lower,” “radial,”“axial,” and the like, are meant to describe relative directions and arenot intended to define absolute directions with respect to gravity ofanother reference system. Moreover, where method, process or proceduresteps are provided, or more generally, where a control or operationalfunction is described, it is expressly contemplated that such step orfunction can be implemented using electronic hardware, software thatincludes computer-readable medium comprising program instructions, or acombination of hardware and software. Accordingly, this description ismeant to be taken only by way of example, and not to otherwise limit thescope of this invention.

1. A power generating system comprising: a miniature internal combustionengine (MICE) generator having a piston and shaft axially moving withina casing and the shaft being operatively connected to a first end of aspring a second end of the spring being fixed to the casing, the shaftbeing further interconnected to an alternator assembly in which axialmovement of the shaft causes relative movement of an alternator coilwith respect to a magnet assembly; and a dual clipper circuitoperatively connected with the alternator coil, the clipper circuitsensing the current and at least two voltage levels and applying atleast two respective loads in response to the sensed voltage levels andcurrent so as to (a) prevent overstroke of the piston and (b) controlpower output of the alternator coil; and wherein the alternator coil isoperatively connected with a current compensation circuit to provide anaccurate reading of the sensed voltage levels by compensating for avoltage produced by a high current across the alternator coil by a cycleof the movement of the piston.
 2. The power generating system as setforth in claim 1 further comprising a MOSFET circuit that applies avariable load in response the clipper circuit.
 3. The power generatingsystem as set forth in claim 1 wherein the dual clipper circuitcomprises a hard clipper circuit and a soft clipper circuit.
 4. Thepower generating system as set forth in claim 3 wherein the hard clippercircuit is constructed and arranged to prevent overstroke of the piston.5. The power generating system as set forth in claim 4 wherein the softclipper circuit is constructed and arranged to control power output ofthe alternator coil.
 6. The power generating system as set forth inclaim 3 wherein the soft clipper circuit is constructed and arranged tocontrol power output of the alternator coil.
 7. The power generatingsystem as set forth in claim 1 further including a switch coupledbetween the alternator and a rectifying diode bridge to selectivelyoutput alternating current.
 8. The power generating system as set forthin claim 1 wherein the dual clipper circuit further includes a currentmeter circuit.